a {
    color: black;
    text-decoration: none;

}

a:hover {
    text-decoration: underline;
    color: #007bff;
}

ul {
    display: flex;
}

li {

    list-style-type: none;
    /*display: flex;*/
    margin: 5px;
    /*边框*/
    padding: 5px 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
    text-align: center;
    -webkit-border-radius: 5px;
    -moz-border-radius: 5px;
    -ms-border-radius: 5px;
    -o-border-radius: 5px;
}